Open AccessNanometer-Scale Force Profiles of Short Single- and Double-Stranded DNA Molecules on a Gold Surface Measured Using a Surface Forces Apparatus
Author(s) -
Di Kang,
Jing Yu,
Fan Xia,
Jun Huang,
Hongbo Zeng,
Matthew Tirrell,
Jacob N. Israelachvili,
Kevin W. Plaxco
Publication year - 2021
Publication title -
langmuir
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.042
H-Index - 333
eISSN - 1520-5827
pISSN - 0743-7463
DOI - 10.1021/acs.langmuir.1c01966
Subject(s) - monolayer , molecule , chemical physics , brush , force spectroscopy , nanometre , chemistry , surface forces apparatus , dna , polymer brush , polymer , nanotechnology , surface force , materials science , crystallography , atomic force microscopy , composite material , physics , organic chemistry , classical mechanics , biochemistry , polymerization
Using a surface forces apparatus (SFA), we have studied the nanomechanical behavior of short single-stranded and partially and fully double-stranded DNA molecules attached via one end to a self-assembled monolayer on a gold surface. Our results confirm the previously proposed "mushroom-like" polymer structure for surface-attached, single-stranded DNA at low packing density and a "brush-like" structure for the same construct at higher density. At low density we observe a transition to "rigid rod" behavior upon addition of DNA complementary to the surface-attached single strand as the fraction of molecules that are double-stranded increases, with a concomitant increase in the SFA-observed thickness of the monolayer and the characteristic length of the observed repulsive forces. At higher densities, in contrast, this transition is effectively eliminated, presumably because the single-stranded state is already extended in its "brush" state. Taken together, these studies offer insights into the structure and physics of surface-attached short DNAs, providing new guidance for the rational design of DNA-modified functional surfaces.